Since many years, it was believed that the sole mechanism for postnatal growth of new blood vessels in response to exercise is angiogenesis, occurring through vascular sprouting and intucesseption. Today, accumulating evidence indicates that peripheral blood contains marrow-derived endothelial progenitor cells, which have the potential to differentiate into mature endothelial cells and which can contribute to postnatal vessel growth and repair (postnatal vasculogenesis). However, controversy exists with respect to the identification and the origin of endothelial progenitor cells, this review focus on the different possible sources of endothelial progenitor cells like hematopoietic stem cells, monocytes/macrophages, and mesenchymal stem cells (multipotent adult progenitor cells; MAPCs). In the last years, several groups were able to show the positive effects of exercise on endothelial progenitor cells, which means that vasculogenesis/endothelial progenitor cells might as well contribute to the growth of new blood vessels in adaptation processes. The effect of exercise on endothelial progenitor cells and possible mobilization-factors like hypoxia are discussed.